This invention relates generally to surgical conduit occlusion devices such as clips and clamps, and more specifically to tissue contacting surfaces commonly associated with inserts for clips and clamps.
The human body contains many body conduits which accommodate a flow of fluids or semi-solids among various locations of the body. Typical of such conduits are the intestines, and, in particular, the blood vessels including both veins and arteries.
Many surgical procedures require the reduction of flow, and more typically, the occlusion of flow in such body conduits. This occlusion is typically accomplished with devices commonly referred to as clamps or clips. In general, these devices have opposing jaws which are adapted to extend exteriorally over the body conduit and to pinch the walls of the conduit against themselves in order to inhibit or stop flow through the conduit.
The jaws commonly associated with clamps are relatively long and are operable by scissor-type handles which provide leverage for the jaws. Clamps are commonly used to occlude larger conduits such as the intestines. By comparison, the jaws of clips are relatively small and are biased by a spring contained in a telescoping housing. The smaller clips are commonly used to occlude smaller conduits such as vessels. As used herein, the word xe2x80x9cclampxe2x80x9d will refer not only to clips and clamps but other types of occlusion devices which have opposing jaws.
Body conduits typically have a relatively smooth outer surface which is often wetted by body fluids such as blood. Attempts to occlude such conduits by exteriorally pinching their walls must meet two objectives. Of course, the first objective is to accomplish the occlusion. But of no less importance is the second objective, to maintain the clamp in place. Herein lies the problem commonly referred to as traction.
Traction in this case relates to the resistance of the clamp to movement relative to the tissue. Theoretically, this traction is equivalent to the product of a coefficient of friction, which is dependent upon the nature of the contacting surfaces, and the normal or clamping force. In the past, attempts have been made to increase this clamping force in order to increase the traction. Unfortunately, squeezing the body conduit with a greater force tends to traumatize the tissue and in the case of vessels, destroy the precious intimal lining which cannot be regenerated. As a result, it is desirable to have only sufficient clamping force to achieve the first objective, that is, the occlusion of the conduit. Increasing the clamping force to achieve the second objective, that is, increase traction, is generally not a suitable alternative.
Attempts have been made to increase the coefficient of friction in order to enhance the traction of the clamp relative to the conduit. This has been complicated by the wetness of the tissue surface of the conduit. U.S. Pat. No. 3,746,002 discloses an Atraumatic Surgical Clamp having a plurality of pin members which extend through a resilient pad and engage the tissue when the pad is compressed. Since the pins stick into the tissue, this produces a highly traumatic effect in most cases. Less heroic attempts to increase the coefficient of friction have not always been sufficient to maintain the clamp in place, even after the conduit has been occluded.
Resilient pads, commonly referred to as inserts, have been provided for attachment to the inner surfaces of the opposing jaws. These inserts typically have a tissue-contacting surface which faces the opposing jaw, as well as a pair of side-surfaces that extend laterally of the insert. Various systems for attaching the inserts to the jaws of the clamp are well-known to those skilled in the art.
In an effort to increase the traction of the inserts, they have been formed of resilient foam and, in some cases, molded with irregular surfaces. In other cases, fibers have been placed along the tissue-contacting surface of the insert in an upstanding relationship similar to the bristles of a toothbrush. Where the ends of these fibers have contacted the conduit, traction has been good, but attempts to increase the occlusion pressure has typically caused the fibers to bend so that only the sides of the fibers remain in contact with the conduit. This generally reduces the coefficient of friction and therefore promotes slippage. Furthermore, fibers have only been placed along the tissue-contacting surface of the insert. Where the insert has been compressed, the resilient pad has expanded bringing the side surfaces into contact with the conduit. Unfortunately, this has not increased contact with the upstanding fibers since these have been limited only to the tissue-contacting surface. Typical of this art is the disclosure in U.S. Pat. No. 4,821,719, issued on Apr. 18, 1989, and entitled xe2x80x9cCohesive-Adhesive Atraumatic Clamp.xe2x80x9d
These deficiencies of the prior art are overcome with the many embodiments of the present invention which provide increased traction between a clamp and body conduit. This traction is provided in several cases by a multiplicity of fibers oriented in their natural state to extend longitudinally between the clamp and conduit. These fibers, which may themselves be composed of filaments, can be woven or non-woven into a fabric for covering a resilient pad or clamp insert. All forms of weaves are contemplated, each providing a texture which may be of particular advantage in different procedures. The nature of the weave may control characteristics such as smoothness, absorption, and texture. The fibers and filaments may be formed from any solid or semi-solid material, each material adding its own characteristics to the resulting fabric insert or clamp.
Providing this traction-enhancing covering over the sides of the insert brings additional traction-enhancing surface into contact with the conduit as the insert is compressed.
The invention comtemplates not only variations in the weave or structure of the fabric forming the covering, but also the structure of each filament or fiber which may contribute to that fabric. Forming the fabric of specific materials or providing those materials in a covering for the fabric or filaments can also improve traction characteristics.
In one aspect of the invention, a surgical instrument for clamping a body conduit to includes first and second opposing jaws and at least one insert. An insert carried by one of the jaws includes a first layer formed of a first material having first-traction characteristics with a body conduit, the first layer being defined in a natural state by an opposing surface and a pair of side-surfaces. A second layer of the insert is formed of a second material having second-traction characteristics greater than the first-traction characteristics. This second layer extends at least partially over the opposing surface and the side surfaces of the first layer and provides a first area of contact with the conduit when the insert is in the natural state and a second area of contact when the insert is in the compressed state. This construction adds the improved traction of the second layer to the increased area of contract provided by the insert in the compressed state. In another aspect of the invention, a surgical clamp includes first and second opposing jaws. A first layer carried by the first jaw has first-compliant characteristics and first-traction characteristics. A second layer carried by the first jaw in juxtaposition to the first layer has second-complaint characteristics and second-traction characteristics. The second-complaint characteristics of the second layer are less than the first-compliant characteristics of the first layer, and the second-traction characteristics of the second layer are greater than the first-traction characteristics of the first layer. A multiplicity of fibers are included in this second layer and oriented generally in a common plane. In an additional aspect of the present invention, the multiplicity of fibers included in the second layer have an elongate configuration and a side-surface extending longitudinally between a first end and a second end. This side-surface of at least one of the fibers is uneven in order to provide the second layer with improved traction relative to the body conduit.
In a further aspect of the invention, at least one jaw of a surgical clamp is provided with an outer fabric which is defined at least in part by a tissue-contacting surface. This fabric will typically be formed of a multiplicity of fibers that are disposed generally in a planer orientation. The fibers may be arranged in a random order or woven. The weave may be conventional or may include any one of the other well-known weave constructions.
These and other features and advantages of the present invention will be more apparent with a description of preferred embodiments in reference to the associated drawings.